Mitochondria

• Mitochondria stained using Ragaud’s method
• Under high power, the nuclei of the cells is clearly visable
  • Mitochondria appear as dark rods arranged radially in bundles
  • They appear to be black splotches
  • Difficult to see because the individual mitochondria are smaller than the resolving power of the light microscope.
    • Resolving power of microscope is 0.5-0.22 μm
    • Mitochondria are on the order of nm and μm
  • Require electron microscope to visualize individual mitrochondria and intra-mitochondrial structures

Ribosomes and Rough ER

• Dark blue masses are neurons appearing in the central region of the tissue using low power
• At 40x, the axons, dendrites and stoma are visible
  • Blue stains the ribosomal RNA, leaving the nucleus mostly unstained because it contains mostly DNA
  • However, nucleolus, the ribosome production factory, is very darkly stained and prominent
    • Ribosomes diffuse from the nucleolus
• Ribosome staining throughout cytosol
  • Nissal bodies are the Rough ER and associated ribosomes

Golgi Apparatus

• Golgi is cresent shaped structure, mostly localized around the nucleus
  • Can be distinguished from nissal bodies because nissal bodies are diffused throughout the cytosol
• Nucleolus not visible on this stain

Skeletal Muscle

• Bands of structure are the filaments
  • Individual filaments are too small for the light microscope to resolve
• Light bands are actin
• Dark bands are myosin
• Filaments are not organelles
  • Not membrane bound, so they are inclusions

Liver

• Stained for glycogen – so pink spheres are glycogen
  • Cells are arranged in cords separated by unstained blood vessels
  • Nuclei are unstained circles within a glycogen stained cord
• Liver cells can be binucleated

Interphase Nuclei and Nucleoli

• Smooth muscle cells run circular around a blood vessel
  • Multiple nuclei
  • Tissue layer: Endothelium layer; Tissue type: simple squamous epithelium
• RBC’s will have no nuclei
• Chromatin:
  • Heterochromatin – condensed dark nuclei usually found on the nuclear lamin surface
    • Nucleolus is usually found near the center of the nucleus
  • Euchromatin – lightly stained, diffuse
  • Vesicular – mix of heterochromatin and euchromatin

Artery, Vein and Nerve

• Artery is surrounded by a thick layer of smooth muscle cells, with simple squamous epithelium lining the center area
  • Simple squamous epithelial layer appears as a dark ring
• Fat adipose cells are mostly white unstained with a tiny nucleus in the corners of the cell

Mitosis

• Interphase
  • Nucleus present with uncondensed chromosomes
• Prophase
  • Chromatin condenses to discrete chromosomes which appear as squiggly lines
  • Nuclear membrane still partly visible
• Metaphase
  • Chromosomes lined up in center of spindle at equatorial metaphase plate
  • Big black spots are excess yolk stained black
• Anaphase
  • Chromosomes migrate to opposite poles
  • No cleavage furrow
• Telophase
  • Cleavage burrow forms
  • Midbody is where the microtubules are all condensed
    • Perpendicular to the cleavage furrow
• Cytokinesis is the division of cytoplasm and occurs in parallel to the division of the chromosomes